Add haptic feedback for swipe-to-go-back.

ios/chrome/browser/ui/uikit_ui_util.mm

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/chrome/browser/ui/uikit_ui_util.h"
 
 #import <Accelerate/Accelerate.h>
 #import <Foundation/Foundation.h>
 #import <QuartzCore/QuartzCore.h>
 #include <stddef.h>
 #include <stdint.h>
 #import <UIKit/UIKit.h>
 #include <cmath>
 
+#include "base/ios/ios_util.h"
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
+#include "base/mac/scoped_nsobject.h"
 #include "ios/chrome/browser/experimental_flags.h"
 #include "ios/chrome/browser/ui/rtl_geometry.h"
 #include "ios/chrome/browser/ui/ui_util.h"
 #include "ios/web/public/web_thread.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/ios/uikit_util.h"
 #include "ui/gfx/scoped_cg_context_save_gstate_mac.h"
 
@@ skipping 626 matching lines @@
   DCHECK(!gFirstResponder);
   [[UIApplication sharedApplication]
       sendAction:@selector(cr_markSelfCurrentFirstResponder)
               to:nil
             from:nil
         forEvent:nil];
   UIResponder* firstResponder = gFirstResponder;
   gFirstResponder = nil;
   return firstResponder;
 }
+
+// On iOS10 and above, trigger a haptic vibration for the user selecting an
+// action. This is a no-op for devices that do not support it.
+void TriggerHapticFeedbackForAction() {
+  if (base::ios::IsRunningOnIOS10OrLater()) {
+    base::scoped_nsobject<UIImpactFeedbackGenerator> generator(

[rohitrao (ping after 24h), 2017/02/23 16:15:54]

This file is ARC, so you shouldn't need to use the scoped_nsobject.

[pink (ping after 24hrs), 2017/02/23 16:22:02]

Done.

+        [[UIImpactFeedbackGenerator alloc] init]);
+    [generator impactOccurred];
+  }
+}
+
+// On iOS10 and above, trigger a haptic vibration for the change in selection.
+// This is a no-op for devices that do not support it.
+void TriggerHapticFeedbackForSelectionChange() {
+  if (base::ios::IsRunningOnIOS10OrLater()) {
+    base::scoped_nsobject<UISelectionFeedbackGenerator> generator(
+        [[UISelectionFeedbackGenerator alloc] init]);
+    [generator selectionChanged];
+  }
+}